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Burn through in #3 piston (94 slt 750)...

5929 Views 4 Replies 4 Participants Last post by  JUST-IN-TIME
A few years back my '94 SLT 750 laid down on me. I tore into it and found a hole in the number three cylinder piston. I got the parts I needed and rebuilt the cylinder myself. I talked to a guy in Louisville who is a pretty good PWC mechanic and he said the problem was due to that particular cylinder running too lean, which to me made sense. I took it to him and he got some carb rebuild kits, installed them and dialed them in. The ski ran great. THis was like 1996 I believe. Well, recently I was doing a little maintenance and decided to pull the heads and check the pistons. Unfortunately for me, the number three piston has a lot of pitting. I don't know how close it is to actually burning through, but I don't believe it is far off. I have heard this is fairly common with the 750 triple and would like to know if anyone out there has a good remedy for this. It looks like to me that maybe since this cylinder is the farthest from the fuel tank that maybe it is continuously starved for fuel. That's just a guess, but it is the best guess I have at this point. If anyone has any info, please pass it on to me...thanks
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The most useful solution for this is to install larger jets in that carb. You can also verify that you have a fuel return restrictor in the return line and if not then to install one. That should help keep the fuel flow through that last carb fine. Some people have even installed a dedicated fuel line and pump directly to that carb.

On a side note, you can easily check rich/lean conditions on a cylinder by pulling the spark plugs and looking at the coloration of the white ceramic insulator. The darker the brown the richer the mixture; you want it to be about a light chocolate color. The best way to check the plugs like this is to do a full throttle pull and kill the engine while on the throttle. Then look at the plugs.
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